Automatic recycling ice detector

ABSTRACT

An automatic recycling ice detector includes a sensor for sensing the formation of ice on an aircraft surface and a heater for melting the detected ice. The detector also includes a timing circuit for indicating the time to melt any detected ice and automatically recycling the detector when the ice is melted. A computer including a look up table or the like are provided for measuring and indicating the thickness of the accumulated ice based on a relationship between melting time and thickness.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.11/471,584, filed Jun. 21, 2006, now U.S. Pat. No. 7,828,247, issuingNov. 9, 2010, which claims the benefit of Provisional Application No.60/758,216, filed Jan. 12, 2006, the disclosure of which is hereinincorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to an automatic recycling ice detector and moreparticularly to an automatic recycling ice detector that indicates totalice accumulation.

BACKGROUND OF THE INVENTION

The accumulation of ice on various surfaces of an aircraft can producedisastrous results. Accordingly it is important for a pilot to know whenice starts to appear and to take measures to avoid serious consequences.For example, the pilot may turn on surface heaters, make changes inspeed or elevation, changes in the angle of attack and/or seek thenearest airport before the problem becomes critical. Further, it isimportant for a pilot to know when accumulated ice in a dangerous amounthas formed on the surface of the aircraft.

Ice detectors are known. For example, a patent of Gaertner, U.S. Pat.No. 3,571,709 discloses a detector for measuring icing rates over aplurality of periods of time. As disclosed therein, an icing ratedetector utilizes an icing switch and a heater, which are mounted on theoutside of an aircraft. When ice forms on the switch, it closes andenergizes a heater, which then melts the ice and causes the switch toopen. The heater thus is cycled on and off when the aircraft issubjected to icing conditions. A rate detector circuit measures the rateat which power is consumed over a fifteen second period and over atwo-minute period. These rates are directly proportional to the rate atwhich ice is formed on the aircraft.

A more recent patent of Mayer, U.S. Pat. No. 4,755,062 discloses aprocess and measuring probe for the determination of ice or snowformation. As disclosed therein, the heat abstraction intenselyoccurring due to ice or snow is measured and used as a signal for ice orsnow formation. A current meter for determining increased powerconsumption determines the intensified heat abstraction on the coldconductor. The intensified heat abstraction on the cold conductor isdetermined by a current meter for determining increased powerconsumption or by a thermister which is an heat conducted connectionwith a cold conductor and switches the power supply of the coldconductor on and off as a function of the temperature.

Notwithstanding the above, it is presently believed that there may be alarge commercial market for an improved ice detector in accordance withthe present invention. A commercial market should develop because theimproved system and element in accordance with the present inventionwarn a pilot of hazardous icing conditions; enable a pilot to determinethe thickness of the ice as well as the condition when icing may be at arelatively high rate. In addition, ice detectors in accordance with thepresent invention indicate the total ice accumulated on the aircraft. Itis also presently believed that such systems can be manufactured andsold at a competitive cost, can be readily installed on new aircraft aswell a retrofitted on existing aircraft, are compact, durable, accurateand readily serviced. Further advantages will become evident from thefollowing specification.

BRIEF SUMMARY OF THE INVENTION

In essence the present invention contemplates an automatic recycling icedetector and ice accumulation indicator for an aircraft. The detectorand indicator include sensing means for sensing the formation of ice ona surface of an aircraft and an electric heater and circuit is alsoprovided for melting detected ice on the selected surface. A timer or atiming circuit indicates the time required for melting the sensed ice.In the present invention, means are provided for automaticallyactivating the sensing means when detected ice has been melted and meansfor calculating the thickness of ice formed on the surface of theaircraft based on a summation of the times required to melt detectedice. Further, an indicator indicates to the pilot the formation of iceand thickness accumulated. Finally, the time for melting the ice canalso be used as an indication of the rate of ice formation.

The invention also contemplates a method for warning a pilot ofaccumulated ice on the surface of an aircraft. The method includes thestep of providing a sensor for detecting the formation of ice onselected portions of a surface on an aircraft and an electric heater formelting the detected ice. In addition, the method includes the step ofdetecting ice formed on the selected surface of the aircraft andenergizing the heater to thereby melt the ice. A timer is provided andan interval of time from the initiation of a heating cycle until the iceon the selected portion of the surface of the aircraft is determined.Further, any subsequent formation of ice on the selected portion of thesurface of the aircraft is sensed and the heater energized to melt thesubsequent formation of ice. The interval from energizing the heateruntil ice is no longer sensed is timed, and the times for melting iceare summed. The method also contemplates providing means such as amicroprocessor, the output of which represents the amount of icedeposited as a function of a predetermined relationship between icedeposition and the timing of its melting. Based on the use of a look uptable or the like the thickness of the ice is indicated for the pilot.

The invention will now be described in connection with the accompanyingfigures wherein like reference numerals are used to display like parts.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that illustrates a first embodiment of theinvention;

FIG. 2 is a schematic illustration of the invention;

FIG. 3 is block diagram that illustrates the operation of a preferredembodiment of the present invention; and

FIG. 4 is a block diagram illustrating a method in accordance with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring now to the drawings, FIG. 1 illustrates an automatic recyclingice detector and ice accumulation indicator for an aircraft thatincludes an ice detector or sensor 20 and a source of electrical power22 for energizing the ice detector 20. The ice detector or sensor 20 maybe in the form of a thermoelectric switch that is mounted on the outersurface of an aircraft. For example, when ice forms on the switch, itcloses a circuit to a heater, which then melts the ice on the switch.Other conventional sensors or detectors such as optical sensors etc. mayalso be used to detect the formation of ice.

In the present invention, the detector 20 is connected in parallel to afirst indicator 24 and heater 26 by an on/off switch 18, so that, thepresence of ice simultaneously energizes the heater 26 and a firstindicator 24 that warns a pilot that the heater 26 is on and that ice isforming on the aircraft. The heater 26 is connected to a timing circuitor timer 28 that measures the time from the formation of ice on theheater 26 until the heater 26 is turned off. In other words, the timingcircuit or timer 28 measures the interval of time between the formationsof ice on the heater 26 until the ice is melted.

The timing circuit or timer 28 outputs a signal to an ice accumulationindicator 30 that indicates the total time that the heater 26 is onduring a flight as an indication of the amount of accumulated ice on theaircraft. In one embodiment of the invention, the signal from the timingcircuit or timer 28 is fed to a calibration circuit 32, which convertsthe time for melting accumulated ice to the amount of ice formed on theheater and consequently on an area adjacent to the heater 26. Thecalibration circuit can convert the ice to thickness of ice and/or theweight of accumulated ice based on the aircraft surfaces.

FIG. 2 illustrates an exposed surface 34 of an aircraft with a discshaped heater 26 thereon. The disc shaped heater 26 includes aninsulating layer 27 between the heater 26 and the surrounding surface 34to isolate the heater 26 from the surrounding area. An optical icedetector 21 is shown schematically and is disposed on the aircraft at adistance from the heater 26.

The operation of an automatic recycling ice detector and iceaccumulation indicator will now be described in connection with FIG. 3.As illustrated, an ice sensor, heater and first indicator are providedin a first step 40. The sensor then senses or detects the formation ofice in a step 42 on an exposed surface of the heater. This detection ofice automatically and simultaneously activates the heater and firstindicator in step 44. This first indicator provided in the cockpit ofthe airplane alerts a pilot of the formation of ice on the aircraft.

A timer or timing circuit measures the time to melt the ice in step 46and in step 48 a second indicator displays the time to melt the ice asan indication of the amount of ice accumulated on the surface of theaircraft. A calibration circuit may also be provided to indicate thethickness or weight of the ice on the aircraft. In addition, a warningmay be sounded when a hazardous amount of ice has been accumulated onthe aircraft.

When the ice is melted the heater and first indicator are automaticallyturned off in step 50 and the system detects any subsequent formation ofice in step 52. The subsequent detection of ice again activates theheater and first and second indicators in step 54. The time to melt thesubsequent formation of ice is measured in step 56. Immediately upon themelting of the ice, the heater and first indicator are deactivated instep 58 and the time for melting the ice is summed in steps 60. Thetotal time is an indication of ice accumulated on the aircraft.

FIG. 4 illustrates a method in accordance with a further embodiment ofthe invention. As illustrated the method includes the steps of providingan ice sensor or detector for detecting the formation of ice on thesurface of an aircraft and a heater for melting the detected ice in step61. In step 63 ice formed on the surface of the heater is detected andthe heater is energized to melt the ice. In step 65 the time of meltingthe ice is measured and the system is continually returned to a sensingmode to detect any subsequent formation of ice in step 66. In step 67any subsequently formed ice is melted and the time of melting thesubsequently formed ice is measured in step 69. The times for meltingthe ice are summed in step 71 as an indication of the accumulatedthickness of the ice on the aircraft. It is also contemplated to providea look-up table for converting melt time to ice thickness in step 73 andcomparing the melt time with the look-up table in step 75 and thenindicting the thickness or weight of accumulated ice to the pilot instep 77.

While the invention has been described in connection with its preferredembodiments, it should be recognized that changes and modifications maybe made therein without departing from the scope of the appended claims.

1. A method for detecting accumulated ice on an aircraft, comprising:sensing ice formed on a surface of an aircraft using a sensor;energizing a heater to melt the sensed ice; timing a first interval fromenergizing the heater until ice on the surface of the aircraft is nolonger sensed using a microprocessor; sensing any subsequent formationof ice on the surface of the aircraft and energizing the heater to meltthe sensed ice; timing a second interval from energizing the heateruntil ice on the surface of the aircraft is no longer sensed using themicroprocessor; and determining a total melt time by summing the firstinterval and the second interval using the microprocessor.
 2. The methodof claim 1, comprising indicating the total melt time to a pilot of theaircraft via a first indicator.
 3. The method of claim 1, comprisingsounding a warning when the total melt time exceeds a predeterminedvalue.
 4. The method of claim 1, comprising determining total iceaccumulation based on the total melt time.
 5. The method of claim 4,wherein the total ice accumulation is determined by comparing total melttime to values in a look up table which define a relationship betweenmelt time and an amount of ice accumulation.
 6. The method of claim 4,comprising indicating the total ice accumulation to a pilot of theaircraft via a first indicator.
 7. The method of claim 4, comprisingsounding a warning when the total ice accumulation exceeds apredetermined value.
 8. The method of claim 4, comprising indicating aweight of the total ice accumulation to a pilot of the aircraft via afirst indicator.
 9. The method of claim 4, comprising indicating athickness of the total ice accumulation to a pilot of the aircraft via afirst indicator.
 10. The method of claim 1, comprising indicating thatice has been sensed on the surface of the aircraft to a pilot of theaircraft via a second indicator.
 11. The method of claim 1, wherein thesensor comprises a thermoelectric switch mounted on the surface of theaircraft.
 12. The method of claim 11, wherein the formation of ice onthe thermoelectric switch closes a circuit to simultaneously energizethe heater and cause a second indicator to indicate to a pilot of theaircraft that ice has been sensed on the surface of the aircraft. 13.The method of claim 1, wherein the heater comprises a relatively flatdisc shaped plate conforming to the surface of the aircraft andinsulation means for separating the plate from a surrounding surface ofthe aircraft.
 14. A non-transitory computer readable medium storing acomputer program to cause a system of an aircraft to execute stepscomprising: sensing ice formed on a surface of an aircraft using asensor; energizing a heater to melt the sensed ice; timing a firstinterval from energizing the heater until ice on the surface of theaircraft is no longer sensed; sensing any subsequent formation of ice onthe surface of the aircraft and energizing the heater to melt the sensedice; timing a second interval from energizing the heater until ice onthe surface of the aircraft is no longer sensed; and determining a totalmelt time by summing the first interval and the second interval.